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Emerson Models 20A and 25A Radio Service Data Sheet
July 1933 Radio-Craft

July 1933 Radio-Craft

July 1933 Radio Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

Here is the Emerson Model 20A and 25A Radio Service Data Sheet as featured in a 1933 edition of Radio-Craft magazine. Note that although both share the same chassis and circuitry, the 20A is a simple rectangular design with a fancy three-dimensional carved façade whereas the 25A is a "tombstone" design with a simpler flat cut-out wood face. The images of both types are from the RadioMuseum.org website As mentioned many times in the past, I post these online for the benefit of hobbyists looking for information to assist in repairing or restoring vintage communication equipment.

Emerson Models 20A and 25A Radio Service Data Sheet

Emerson Models 20A and 25A Radio Service Data Sheet, July 1933 Radio-Craft - RF Cafe

Emerson Models 20A and 25A Radio Service Data Sheet Instructions, July 1933 Radio-Craft - RF Cafe

Only an indication possible. Readings will change materially regardless of type of power supply. Volume control full on, tuning control set for 550 kc., and the antenna outside of set. Use a meter of 1,000-ohms-per-volt type.

Excessive heat may injure the set; do not place it on a radiator or against a wall.

The models 20A and 25A vary only in the cabinet design. Regardless of the length of antenna used, do not leave any of the antenna wire curled inside the set as this may cause circuit oscillation. To operate the set on a 220 V. line use a limiting resistor in the line. On 32 V. systems use three 45 V. "B" batteries, a 32 V. limiting resistor, and a separate attachment plug; the regular power cord is not used. For 6 V. operation only the three "B" batteries, and an adapter cable and plug are required.

 

 

Posted November 3, 2021
(updated from original post on 9/15/2014)


Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 227 Radio Service Data Sheets as of December 28, 2020.

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